March’s spending on temporary staff at the hospital soared by £150,000 on the previous month, with the equivalent of nearly 40 full-time nurses and other medical staff from agencies being drafted in to cope with high levels of activity.

And while changes have already been made to ease its reliance on comparatively expensive temporary staff, West Suffolk’s executive director of resources, Craig Black, told yesterday’s board meeting that controlling the bill was imperative to the hospital’s financial future.

He said: “We do need to continue work on controlling pay, and our temporary pay in particular. That will be an important part of hitting the budget for 2014/15.”

Despite the high levels of activity, its income for March was slightly under what was budgeted, while its pay costs were £1.1million over budget.

Mr Black said this was because it was the last month of the financial year and that a lot of activity had been emergency admissions, for which it receives only 30% of funding above a baseline level.

He added that Nichole Day, executive chief nurse at the hospital, was undertaking a detailed study of ward nursing costs, which he hoped would lead to “a much closer correlation between activity and nursing spend”.

Mr Black said: “I think we need to replicate that with medical spend, so you should see that our expenditure on temporary medical staff, again you see a much closer correlation.

“I think there’s some control that we need to put in place.”

He added that the hospital’s finance team was meeting with professional services specialists PwC on a weekly basis, and that some early work between the two “would suggest that we could benefit from more controls around temporary medical expenditure”.

Speaking after the meeting, Mr Black said: “Having access to temporary staff allows us to flexibly respond to increases in demand. We constantly monitor our use of temporary staff, and overall our expenditure in this area is lower than other hospitals.”

A spokeswoman from Monitor said the watchdog had concerns with the hospital’s “sustainability and financial governance”, adding: “The trust is providing us with further information, which we will assess before deciding on the next steps to ensure the trust is providing quality care for its patients in a financially sustainable way.”